Writing instrument



FIG. 1 is a side view of a writing instrument showing my new design;

FIG. 2 is a front view thereof;

FIG. 3 is a side view thereof, turned 180° from FIG. 1;

FIG. 4 is a rear view thereof;

FIG. 5 is a bottom plan view thereof;

FIG. 6 is a top plan view thereof;

FIG. 7 is a perspective view thereof with the cap positioned over the barrel; and,

FIG. 8 is a perspective view thereof with the cap separated from the barrel. 

I claim the ornamental design for a writing instrument, as shown and described. 